1. Field of the Invention
The present invention relates to recording devices such as an ink jet printer.
2. Discussion of the Background
A recording device employing an ink jet system records an image on a recording medium by discharging ink from a print head while moving the print head back and forth in the primary scanning direction to cause the ink to attach to the recording medium. Then, the recording medium is conveyed in the sub-scanning direction by transfer rollers, etc. to repeat recording in the main scanning direction and form the image on the recording medium.
However, the system of conveying a recording medium by transfer rollers involves a problem such that the assembly and eccentricity of the transfer rollers affect transfer (conveyance) of the recording medium. When the transfer amount of the recording medium varies, the image is formed at a position different from the target (ideal, theoretical) recording position on the recording medium.
Therefore, a technology that tried to deal with such a problem describes a method of adjusting the rotation of a transfer roller by recording a test pattern on a recording medium and detecting the shift amount of the recording medium along the transfer direction thereof based on the test pattern.
However, the accuracy of the test pattern on a recording medium in the technology depends on the status of nozzles, which may lead to droplet missing, droplet shifting, etc. Therefore, this rotation adjustment of a transfer roller results in an erroneous adjustment if the rotation is adjusted according to data obtained from such an inaccurate test pattern.
Because of these reasons, the present inventors recognize that a need exists for a recording device, a control method and a program by which the variation of rotation amount of a transfer roller is reduced along the sub-scanning direction even when nozzle problems cause droplet missing, droplet shifting, etc.
Accordingly, an object of the present invention is to provide a recording device, a control method and a program by which the variation of rotation amount of a transfer roller is reduced when nozzle problems cause droplet missing, droplet shifting, etc.
Briefly this object and other objects of the present invention as hereinafter described will become more readily apparent and can be attained, either individually or in combination thereof, by a recording device including a paper feeder tray that accommodated a recording medium, a print head that discharges ink on the recording medium to record an image thereon, a transfer roller that transfers the recording medium and a printed test chart on which multiple marks are arranged, a control device that controls the transfer roller, a first detection device that detects a rotation position of the transfer roller, a second detection device that detects the multiple marks arranged on the printed test chart, and a transfer device that transfers the recording medium from the paper feeder tray to the second detection device, wherein the control device obtains a difference between an actual transfer amount of each of the multiple marks obtained by detecting the multiple marks by the second detection device and a predetermined theoretical transfer amount of each of the multiple marks relating to a rotation position of the transfer roller, calculates a correction amount for the rotation amount of the transfer roller based on a relationship between the rotation position of the transfer roller and the difference, and controls the rotation amount of the transfer roller using the correction amount.
It is preferred that, in the recording device mentioned above, based on the relationship between the rotation position of the transfer roller and the difference, the control device determines a first difference with regard to a current rotation position of the transfer roller and a second difference with regard to the position after rotation of the transfer roller, and calculates the correction amount from the difference between the first difference and the second difference.
It is still further preferred that, in the recording device mentioned above, the control device controls the transfer roller such that the rotation amount of the transfer roller matches the actual rotation amount thereof, the actual rotation amount of the transfer roller obtained by subtracting the correction amount from the theoretical rotation amount of the transfer roller between the current rotation position of the transfer roller and the position after rotation.
It is still further preferred that, in the recording device mentioned above, the printed test chart is overlapped on the recording medium before the printed test chart is transferred to the second detection device.
It is still further preferred that, in the recording device mentioned above, the control device corrects the actual transfer amount of each of the multiple marks according to the layer thickness of the printed test chart.
It is still further preferred that the recording device mentioned above further includes a second paper feeder tray that accommodates the printed test chart, and a second transfer device that transfers the printed test chart accommodated in the second paper feeder tray to the second detection device.
It is still further preferred that, in the recording device mentioned above, the control device corrects the actual transfer amount of each of the multiple marks depending on the difference between the layer thickness of the printed test chart and the layer thickness of the recording medium.
It is still further preferred that, in the recording device mentioned above, when the second detection device detects the multiple marks arranged on the printed test chart that is transferred askew with an angle, the control device corrects the actual transfer amount of each of the multiple marks depending on the angle.
It is still further preferred that, in the recording device mentioned above, when the number of counts of the marks detected by the second detection device is less than a predetermined number of counts, the control device determines that the second detection device detects the printed test chart transferred askew with the angle.
It is still further preferred that, in the recording device mentioned above, the control device identifies the angle from the difference between the number of counts of the marks detected by the second detection device and a predetermined number of counts and corrects the actual transfer amount of each of the multiple marks according to the angle identified.
As another aspect of the present invention, a method of controlling a device that forms images with a print head that discharges ink on a recording medium, includes firstly detecting the rotation position of a transfer roller that transfers the recording medium, secondly detecting multiple marks arranged on a printed test chart that is used to adjust a transfer amount of the transfer roller and controlling the transfer roller that includes firstly calculating an difference between an actual transfer amount of each of the multiple marks obtained by a step of secondly detecting rotation position, and a predetermined theoretical transfer amount of each of the multiple marks relating to the rotation position of the transfer roller, secondly calculating a correction amount to correct the transfer amount of the transfer roller based on a relationship between the rotation position of the transfer roller and the difference, and controlling the transfer amount of the transfer roller using the correction amount.
As another aspect of the present invention, a computer-readable recording medium storing a computer program for executing a method of recording an image on a recording medium with a print head that discharges ink is provided in which the method includes firstly detecting the rotation position of a transfer roller that transfers the recording medium, secondly detecting multiple marks arranged on a printed test chart that is used to adjust a transfer amount of the transfer roller, and controlling the transfer roller including firstly calculating the difference between an actual transfer amount of each of the multiple marks obtained by a step of secondly detecting rotation position, and a predetermined theoretical transfer amount of each of the multiple marks relating to the rotation position of the transfer roller, secondly calculating a correction amount to correct the transfer amount of the transfer roller based on the relationship between the rotation position of the transfer roller and the difference and controlling the transfer amount of the transfer roller using the correction amount.
These and other objects, features and advantages of the present invention will become apparent upon consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.